The present invention relates, in general, to a sealing assembly for a rotating component, such as a spindle or a shaft, for preventing escape of fluid and/or ingress of contaminants from outside. The present invention further relates to a medium transfer apparatus provided with a sealing assembly according to the present invention for preventing a leakage during transfer of medium into the shaft.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
Rotating components, such as tool spindles, run frequently at high revolutions in order to realize sufficiently high cutting speeds, when small tools are involved for example. Typically, the spindles are lubricated with oil. In particular in the wood working industry, or when machining graphite and other oil-sensitive material or milling pre-finished or finished materials are involved, assurances must be provided to prevent escape of fluids from the spindle because otherwise the workpiece may become contaminated, damaged or even useless. For that reasons tool spindles are provided with primary seals to ensure that no oil escapes. Typically, the primary seals are configured as labyrinth seals which, however, are not entirely leak-free and moreover are characterized by relatively great dimensions. As a result, the cantilever arm between tool tip and the proximal bearing has to be configured long enough, adversely affecting the dynamic properties of the spindle.
Motor spindles also require the arrangement of rotary feedthroughs to enable lubricant to be introduced, as the tool spindle rotates, and to be transported to the installed tool. Seals for such feedthroughs are typically realized as ceramic sealing packs. In particular when high revolutions are involved, sealing packs have, however, only a short service life.
It would therefore be desirable and advantageous to provide an improved spindle apparatus and an improved medium transfer apparatus to obviate prior art shortcomings.